Long Term Bandwidth Usage Reports

Long-term bandwidth usage reports show bandwidth usage for IP and satellite traffic. The Average Tab of the SAT Long Term Bandwidth Usage report also displays a percent-of-max-

capacity figure which quantifies unused bandwidth margin on both the upstream and

downstream channels. Long-term bandwidth usage reports include all remotes below the selected element in the iMonitor Tree.

5.1.1 Generating Long Term Bandwidth Usage Reports

To generate a Long Term Bandwidth Usage report:

1. Right-click a network, inroute group, or remote.

2. Select IP Long Term Bandwidth Usage or SAT Long Term Bandwidth Usage to open the Long Term Bandwidth Usage Parameters dialog box.

Figure 195. Selecting Long Term Bandwidth Usage Parameters 3. In Remote Devices, select the remotes for the report.

4. Select Total All Remotes to sum the values for all of the selected remotes. Clear this

check box to report on each remote individually.

5. In Direction, select Downstream, Upstream, or Both to report on downstream bandwidth

usage, upstream bandwidth usage, or usage in both directions.

6. In IP Type or OTA Type, select one or more protocol for the report, or select None to

report only on total traffic. Select All to select all of the available IP protocols. This results in a list of the individual values for each protocol.

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8. In Time Range, select the time period for the report by selecting a Start Time and an End Time. Enter time values using the text boxes or click the buttons to the right of the Start Time and End Time to use the clock tool.

9. Move the Interval slider to specify the time interval represented by each message

returned from the server. This adjusts the granularity of the results depending on the type of report.

The minimum interval available depends on the Start Time of the report. As the statistics age, the NMS server automatically consolidates records to save disk space. Shorter intervals may not be available if the Start Time is far in the past. By default, iMonitor chooses the shortest possible interval for the selected Start Time. For more information on how the NMS server consolidates usage records see Accessing the NMS Statistics Archive on page 171.

10. In the Sort By drop-down list, specify an initial sort order for the report. After the report

is generated, it can be re-sorted by clicking the appropriate column heading.

11. Click OK to run the report. After the server has retrieved the data, iMonitor, displays the

report.

5.1.2 Results

Long Term Bandwidth Usage reports are organized into two tabs: Totals and Average. The

Totals tab shows total kilobytes allocated over the interval represented by each message

returned to iMonitor from the server. There is a total value for each interval at the end of each row, and a grand total at the bottom of each column. The Average tab shows the same data in kilobits per second.

Figure 196 shows an example of the Totals tab of the Sat Long Term Bandwidth Report. The report in Figure 196 is not broken down by IP protocol. When individual IP protocols are selected on the parameters dialog box (Figure 195), the report shows each protocol in its own column.

NOTE: By default, six months of data are stored in the statistics archive. To save

IP statistics for longer than six months, contact iDirect’s Technical Assistance Center (TAC).

Figure 196. SAT Long Term Bandwidth Usage Report: Totals Tab

To view the average data rates in kilobits per second for the same statistics, click the Average tab.

Figure 197 shows an example of the Totals tab of the IP Long-Term Bandwidth Report. Like the report in Figure 196, this report is not broken down by IP protocol.

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Figure 197. IP Long Term Bandwidth Usage Report: Totals Tab

To view the average data rates in kilobits per second for the same statistics, click the Average tab.

5.1.3 Interpreting Long Term Bandwidth Usage Reports

In addition to the Kbps values, the Average tab of the SAT Long Term Bandwidth Usage report contains the percentage of the maximum channel capacity of the upstream and downstream channels for the interval chosen.

The values in these two columns (Figure 198) provide estimates of the bandwidth margins on the upstream and downstream carriers. These values are estimates only; the actual channel capacities may be slightly higher or lower depending on a number of factors. However, the values are accurate enough to determine when to consider adding additional bandwidth to a particular channel.

The downstream estimate is reduced by 2.5% to account for overhead. Downstream overhead includes HDLC framing, timeplans, UCP commands, etc. The theoretical maximum for a downstream with a 2 Mbps information rate is 2 * .975 = 1.95 Mbps. For the upstream, the following calculation is used to determine the theoretical maximum in bits per second: (bytes per slot)*(8 bits per byte)*(slots per frame)*(1000/frame_len) In the formula, bytes per slot does not include iDirect internal overhead. Also, this calculation removes unique word and guard band overhead. In a typical network configuration with small FEC blocks, a 658 Kbps information rate, a 125 ms frame, and 109 traffic slots, the theoretical maximum would be:

(70 bytes per slot)*8*(109 slots)*(1000/125)= 488320 bps = 488.320 Kbps The upstream theoretical maximum is an estimate only. Like the downstream estimate, the actual maximum varies depending on a number of factors, such as the number of remotes in the network, the minimum data rate for each remote, and IP packet sizes.

Note that a larger report interval may result in the calculation of a relatively lower

percentage of maximum capacity. This is due to the fact that the data rates are averaged over the entire the interval, so spikes in activity tend to be hidden in the averages for longer intervals.